1. Technical Field of the Invention
The present invention relates to a sliding material excellent in friction and wear characteristics and a method of manufacturing the same.
The term "sliding material" used herein is to be understood as construction including plain bearing or bearing material or self-lubricating material which is suitable for use as antifriction material for producing sliding members; such as bearing bushes, shoes, slide plates, and sliding members used in clutches, brakes, etc., and collectors.
The term "plain baring or bearing material or self-lubricating material" is to be understood as including a steel backing to which is bonded a layer of porous bronze constituting a matrix in which the porous bronze at least at and adjacent to its exposed surface is impregnated with a mixture of PTFE and lead etc.
2. Prior Art
Conventional sliding materials and methods of manufacturing the same include a sliding material comprising a backing metal having a porous metal layer formed on the surface thereof in which pores are defined and the following composition for impregnation coating (a) or (b), as shown in, e.g., Japanese Patent Kokoku (Post Exam. Publication) No. 39-16950.
(a) PTFE (polytetrafluoroethylene) +20Pb (metal lead) PA1 (b) PTFE+20PbO (lead oxide)
Here, attention must be paid to that the above Japanese Patent Kokai discloses coarse lead powder having a mesh of 300 B.S.S as the type of metal lead used as an example on lines 21 and 22 of the right column of page 1. The lead powder has a ratio of surface area to weight of 500 cm.sup.2 /g, it is found that the lead powder having such a very small relative surface area was used.
A sliding material and a method of manufacturing the same according to the technology as disclosed in the above prior art in which the lead powder having a very small relative area is used does not satisfy friction and wear characteristics when the sliding material is slid in a dry state, in the sliding characteristics thereof.
A problem to be solved by the present invention is to determine a size of metal lead by which the above friction and wear characteristics as an object are improved.